Corrosion resistant tubes



Patented Nov. 24,1936

UNITED STATES PATENT OFFICE CORROSION RESISTAN'T TUBES Edward W. Roath,Waterbury, Conn, asslgnor The Chase Companies, Incorporated, NewHaven,-Conn., a corporation of Connecticut No Drawing. Application March20, 1936, Serial No. 69,885 I Claims.

Ordinary straight or plainbrasses consisting solely of copper and zincare subject to dezincification when the actual copper content ranges 15between about 57% and about 85%. When' one or more other elements areadded to straight brasses, the actual copper content dezincificationrange is usually different.

Straight brasses subject to dezinciflcation and having an actual coppercontent iro'nrabout 64% to about 85% consist entirely of alpha solidsolution,- while those from about 64% down to about 57% consist of bothalpha and beta solid solutions.- Special brasses containing one or moreadditional elements, such, for example, as silicon, aluminum, tin,manganese, etc., in addition to the copper and zinc. and havingapproximately the same degree of, saturation of the alpha solid solutionor approximately equal relative proportions of the alpha and beta solidsolutions as the straight brasses having an actual copper content fromabout 57% to about 85%, generally dezincii'y similarly to' 40 made of76% 'copper, 2% aluminum and the balance zinc, it is found that thisbrass has astructure equivalent to a straight brass of about 69% copper,that is, the 76% aluminum-containing brass has a degree oi saturation ofthe alpha solid solution approximately equalto that which occurs in 69%straight brass. Therefore, the aluminum brass containing an actualcopper.

content of 76% may be said to have an apparent copper content orstructurally equivalent copper content of 69%.

' Investigation of various special brasses containing additionalelements such as silicon, aluminum and other elements, showsthat theefiect of these additional elements follows a law which can berepresented approximately by the following mathematical equation:

But when one or more of the. foregoing men In the above equation:

A=the per centof apparent copper content A=the percent of actual coppercontent :r, y, z, etc.=constants for the various added elements m, n,o,etc.=the per cents of the corresponding added elements.

The following elements and their constants are given:

Silicon =9 Lead 0 Aluminum =5 Iron =-0.1 Magnesium=l Manganese =-0.5 TinNickel =--.2.2

Cadmium i=0 i To find, for example, the structurally equivalent orapparent copper content of a special brass having an actual coppercontent of aluminum 2%, tin 1% and balance zincr 100X80 80o0 per cent ofappar- A 100 5 X 2 1 X 1 1n ent copper content In other words, the abovealuminum brass having an actual copper content of 80% has approxi--mately the same'degree of saturation of the alpha solidsolution asoccurs in straight brass of 72% v actual copper content. Therefore, wemay say, that the aluminum brass having an actual copper content of 80%has an apparent copper content of about 72%. ,Generally speaking, thequestionas to whether or nota given brass, whether straight or special,will be subject to dezincification, depends upon the structure of the,brass, that is, upon whether its apparent copper content ranges betweenabout 57% and about Sea water and other salt waters, and so-called freshwater such as 'domestic water supplies and allsurface and groundwatersupplies, whether of 'shallow 'or deep'origin, all are dezincifyingliquids which tend to induce dezincification, and all of them areincluded by theterm saline liquid. I have found that the addition ofantimony to straight or special, normally dezincit lable brasses,distinctly improves the dezincification resistance of the brass. Anaddition of as little as 0.007 antimony substantially increases tionresistance of brass alloys. The addition of 0.02% antimony to brassalloys further increases the resistance to corrosion and largelychangesthe type of corrosion from dezinciflcation to the less harmfulgeneral thinning. The addition of 0.09% antimony to. brass alloys stillfurther increases the resistance to dezincification and in the case ofsome brasses, completely overcomes dezinciflcation, such small corrosionas occurs being general thinning, a comparatively innocuous.

form of corrosion compared to dezlnciflcation, m

the dezincifica- 'to brasses, are 'eflective to improve theirdezinciflcation resistance, but when the amount passes above 0.35%antimony, increasing dimculty is encountered in manufacturingwrought-brass tubes, pipes, etc., owing to the inferior workingproperties of the brasses.

If from %-to 2% of tin is added to brasses containing antimony, the tinaids the antimony in still further improving the dezlnciflcationresistance.

{f arsenic is used in brasses in place of antimony, it improves thedezinciiication' resistance, but tends to bring about a diflerent typeof corrosion, namely, intercrystalline attack, which is more severe whensmall amounts of both arsenic and tin are present.

The addition of small amounts of antimony and arsenic, or antimony,arsenic and tin, greatly improves the dezinciflcation resistance withoutproducing any intercrystalline attacka The following represent somesatisfactory dezinciflcation resistant brass alloys having an apparentcopper content within a range of from wrought-brass tubes, pipes, etc.:

Acton-loom Aluminum Silicon Tin Nickel Manganese Lead A'ntirnony 4 Thefollowing represent" some additional zinciflcation resistant brassalloys: I

g-q snanus:

The invention maybe carried out in other specific ways than those hereinset forth without spects as illustrative and not restrictive, and allchanges coming within the meaning and equiva- 'lency range of theappended claims are intended to be embraced therein.-

I claim:

1. A dezinciflcation-resistant dezincifying-liquid-contact wrought-brasstube formed from brass containing: an apparent copper content from about57% to about 85%; an actual zinc content less than the apparent coppercontent and which if alone with the copper would form a tube which woulddezincify; 'an actual tin content from about 54% to about 2%; an actualaluminum content from about t'o'about 4%; and

content less than the apparent copper content and which if alone withthe copper would form a tube which would dezincify; an actual aluminumcontent from about /z% to about 4%; and an actual antimony content smallenough to permit the tube to be wrought but sumcient to substantiallyimprove the dezinciilcation resistance of the a tube.

3. A dezinciflcation-resistant dezincifyingliquid-contact wrought-brasstube formed from brass containing: an apparent copper content from about57% to about 85%; an actual zinc content less than the apparent coppercontent and which if alone with the copper would form a tube which woulddezincify; an actual tin. content from about to about 2%; and an actualantimony content small enough to permit the tube to be wrought butsumcient to substantially improve the dezinciflcation resistance of thetube.

4. A dezinciflcation-resistant dezincifyingliquid-contact wrought-brasstubeformed from bran; containing: an apparent copper content from about57% to about 85%; an actual zinc antimony content small enough to permitthe tube to be wrought but'sufiicient to substantially improve thedezinciflcation resistance of the tube.

5. A dezinciflcation-resistant dezincifyi sliquid-contactwrought-brass'tube formed from brass containing: an apparent coppercontent from about 57% to about 85%; anactual zinc content less than theapparent copper content and which it alone with the copper would form atube which would dezincify; an actual tin content from about to about2%; an actual aluminum content from about A to about 4%; and an actualantimony content from about 0.01% to about 0.85% to substantiallyimprove the dezinciflcation resistance of the tube. v

6. A dezinciflcation-resistant dezincii'ying liquid-contactwrought-brass tube formed from brass containing: an apparent coppercontent from about 57% to about 85%; an actual zinc content less thanthe apparent copper content and whichif alone with the copper would forma tube which would dezincify; an actual aluminum content from about 55%to about 4%; and an actual antimony content from about 0.01% to about0.35%, to substantially improve the defzinciflcationresistanceofthetube. v x 7-. A culmination-resistantdeaincifyingaccrual liquid-contact wrought-brass tube formed from ,brasscontaining: an apparent copper content about 53% to about 85%; an actualzinc content less tl'ian the apparent-copper content and which if alonewith the copper would form a tube which would clezincity; anol an actualantimony content from about .lll% to about 0.35% to substantiallyimprove the dezincification resistance of the tube.

9. n oleaincification resistant clezincifying ltnulcbcontactwrought-brass tube formed from brass containing; an apparent coppercontent from about 57% to about 75%; an actual 'zinc content less thanthe apparent copper content and which it alone with the copper wouldform a tube which would clerzincify; an actual tin controzn about toabout l%%; an actual ahuninum content from about 1% to about 272%; and;an actual antimony content small enough to permit the tube to be wroughtbut sumcient to substantially improve the dezincification resistbrasscontaining: an apparent copper content from about 57% to about 75%; anactualzinc content less than the apparent copper content and which italone with the copper would form a. tube which would dezincify; anactual aluminum content from about 1% to about il /2%; and an actualantimony content small enough to permit the tube to be wrought butsufllcient to substantially improve the dezincification resistance ofthe tube. v

11. A dezinciflcation-resistant dezincifyingliquid-contact'wrMght-brasstube formed from brass containing: an apparent copper content from about57% to about 75%; an actual zinc content less than the apparent coppercontent and which it alone with the copper would form a tube which woulddezincify; an actual tin content from about /g% to about l /z%; and anactual antimony content small enough to permit the tube to be wroughtbut suiiicient to substantially improve the dezlnclfication resistanceof the tube.-

12. A dezlncification-resistant dezinciiyingliquid-contact wrought-brasstube formed from brass containing: an apparent copper content from about57% to about 75%; an actual zinc content less than the apparent coppercontent and which it alonewlth the copper would form a tube which wouldrlezincify; and an actual antimony content small enough to permit thetube to be wrought but sufiicient to substantially improve thedezincificatlon resistance of the tube.

13. A dezlncification-resistant dezinciiyingliquid-contact wrought-brasstube formed from brass containing: an apparent copper content from about57% to about 75%; an actual zinc content less than the apparent coppercontent and which it alone with the copper would form a tube which woulddezincify; an actual tin con- I tent from about to about 1 /2%; and anactual antimony -contk'sht from about 0.03% to about 0.25% tosubstantially improve the dezincification resistance of the tube.

14. A dezinciflcation-resistant dezincifyingliquid-contact wrought-brasstube formed from brass containing: an apparent copper content from about57% to about 75%; an actual zinc content less than the apparent coppercontent, and which if 'alone with the copper would form to about 0.25%to substantially improve the dezincification resistance of the tube.

15. A' dezincification-resistant dezincifyingliquid-contactwrought-brass tube formed from brass containing: an apparent'coppercontent from about 57% to about 75%; an actual zinc content less thanthe apparent copper contentand which if alone with the copper would forma tube which would dezincify; an actual tin content from about /2% toabout 1Vz%; an actual aluminum content from about 1% to about 2 and anactual antimony content from about 0.03% to about 0.25% to substantiallyimprove the dez'incification resistance of. the tube;

EDWARD W. ROATH.

7 a tube which would. dezincify; an actual aluminum content from about1% to about 2 /2%; and an actual antimony content ,from about 0.03%

